Muffler



P. G. PEIK July 23, 1935.

MUFFLER 2 Shets-Sheet l Filed July 60, 1932 a o n n v n nl sul nu l Si NPHUL E* PE/K July 23, 1935. P. G. PEIK 2,009,343

MUFFLER Filed Ju'ly 30, 1932 2 Sheets-Sheet 2 3mm PHUL G- PE'K PatentedJuly 23, 1935 UNITED STATES PATENT oFFlcE MUFrLEa tion of OhioApplication July 30, 1932, ySerial No. 626,280

1 Claim.

vide a mufller having a very high degree of silencing or muillingeciency and relatively low back pressure.

A further object of the invention is to provide amuiiier in whichcondensation will be eliminated under all operating conditions.

Another object of the invention is the provision of a muffler capable ofscavenging efficiently under all operating conditions.

A still further object of the invention is to provide an extremelycompact structure adapted to occupy but very little space, particularlyin its longitudinal dimension.

Other objects and advantages of the invention will be apparent as thespecification is considered in connection with the accompanyingdrawings, in which:

Figure l is a longitudinal sectional view through a muffler ac'cordingto the invention, the section being taken on line I-I of Figure 2;

Figure 2 is a cross sectional view on line 2-2 of Figure 1;

Figure 3 is a perspective view of the skeleton inset supporting thetubes and subdividingthe cylinder in parallel compartments;

Figure 4 is a longitudinal sectional view oi a modified form of themuier according to the invention, the section being taken on line 3-3 ofFigure 5; l

Figure 5 is a cross sectional view on line 5-5 of Figure 4; and

Figure 6 is a perspective view partly broken away of the skeleton insetsupporting the tubes and subdividing the cylinder in parallelcompartments.

Referring more particularly to the drawings, my improved mufliercomprises an outer preferably cylindrical sheet metal shell I, closed atits ends by end walls 2, also of sheet metal. Inner walls or partitions3 slightly spaced from end walls 2 form narrow spaces 4 at the ends ofthe cylinder which spaces are filled with pads of 'foraminous soundabsorbing material 5, such as expanded mica, steel wool and-the like.These packed end sound absorbing spaces are not absolutely necessary tothe proper functioning of the muier, and therefore may in most instancesbe eliminated.

Mounted within the shell l. are a series of parallel perforated tubes 6,l and 8 through which exhaust gases pass in the order named. Aperturedsheet metal disks 9 within and adjacent each end of cylinder I serve assupports for tubes 6, 'I and 8 and also form chambers I0 and I I,between said disks and the end walls of the cylinder for reversing theflow of gas. Tube 6 extends at its intake end through end wall 2 at theintake end of the cylinder for connection with the engine exhaust, notshown, and at its other end exhausts into reverse flow chamber I0. Thetube 8, communicates with chamber II at its inner end and exhauststhrough end wall 2 at the exhaust end of cylinder I, and tube 'Isupported solely by the apertured disks 9 communicates at opposite endswith the respective flow reversing chambers I0 and II. Disks S arepreferably of imperforate metal except where provided with openings forthe tubes 6, I and 0. Three longitudinally extending fins I2, I3 and I4radiating from the axial center of cylinder I to the outer wallsthereof, divide the latter into three longitudinal compartments I5, I6and I'I, each of which accommodates one of the tubes. These compartmentsare packed with sound absorbing material such as used in the end spaces4, which material occupies the space around the perforated tubes andcompletely nlls each compartment. The ns are welded or otherwisesuitably secured at their ends to the disks 9 and at their longitudinaledges to the inner face or wall of the cylinder I. Fins I3 and I4 areperforated while fin I2 is of solid metal for reasons which will bepresently explained. That portion of the tub-e 6 which passes throughreversing chamber II at the front or inlet end of cylinder I, as well asthat part of tube 8 which passes through reversing chamber I0 at therear or exhaust end of the cylinder are solid, that is the perorationsformed in the remainder of these tubes are omitted.

Exhaust gases flow through tube 6, into reverse flow chamber I0 thenceback through tube l to reverse flow chamber II and finally into andthrough tube 8 to the atmosphere. This flow is possible because tubes Band l8, in which the iiow of gas is in the same direction, are separatedfrom each other against direct communication by solid fin I2, whereastube 'I Ihas direct communication with the tubes 6 and 8 through theperiorated ns I3 and I4 respectively.

The use of the perforated dividing iins is a most important feature ofmy invention. If these fins were solid, it would be necessary to makethe diameter of the cylinder I much larger in order to providecompartments I5, I6 and Il large enough for the efficient absorption ofsound in the sound absorbing material packed therein. However, by virtueof these perforated iins, the impulses in the gas stream passing throughany one tube are not confined to the compartment housing thattube but tothe contrary are free to expand through the perforations in the finsdirectly into the next adjacent tube in which the flow of gases is inthe opposite direction. Thus impulses in the stream of exhaust gasesflow through tubes 6 and 8 in the same direction, that is from the ticstructure.

front to the rear of the mullier, are not free to merge directly witheach other, but onlyindirectly through tube 1, whereas the impulses inthe stream of gases flowing through tube l in a direction opposite tothat of the flow through tubes 6 and 8, are free to merge with thelatter, and vice versa. It will be noted that the gas flow in the tubesseparated by the perforated fins I3 and I4 is opposite in direction ineach case. This makes it possible for the high impulses in one gasstream to expand through the perforated n into and merge with the lowimpulses of the gas stream passing through the adjacent tube on theopposite side of this fin, and this merging of the high and low impulsesis constantly taking place throughout the entire muffler. Furthermore,as the gas streams are flowing in opposite directions the merging actionis greatly multiplied and consequently an extremely high degree ofmuiiling efficiency is attained in a muiller of very short length.

Due-to the fact that the direction of ow of gases passing through tubes6 and 8 is the same in each tube, and because the shearing or mergingaction previously referred to could not take place under suchconditions, an imperforate n is employed to separate thesetubes fromeach other. If the n I2 were perforated as in the case of ns I3 and I4,the merging efficiency between tubes 6 'and 8 would be no greater thanthat of a conventional straight stream acoustic mufler, because in therelatively small muffler practicable with my invention any muiiingeffect thus attained would be neutralized by the short cut part of thegases would take from tube 6 to tube 8. However, if the dimensions ofthe muffler are increased any appreciable extent beyond theextrememinimum which it is possible to employ according to my invention,n I2 may be perforated to advantage. As a matter of fact even where n I2is solid or imperforate as illustrated herein, an indirect merging ofimpulses between tubes 6 and 8 and their compartments takes placethrough the compartment I6 in which tube I is located.

The acoustic material between disks 3 and end walls 2 has a materialeffect on muflling efliciency and acts favorably upon the gas stream asit expands in the reversing chambers-I and II. However, as previouslystated, the disks 3 and 4 the packing between these disks and the endwalls 2may be omittedwithout any noticeable effect with many engines nowon the market, particularly with eight `or twelve cylinder engines.

The action of the gases previously described, that is the expansion ofthe high gas impulses in one chamber into the low areas in the adjoiningchamber'and vice versa, provides the necessary expansion for efficientmuflling in a muiller in which the chambers are much smaller than wouldbe necessary in a conventional acous- VIt also materially reduces backpressure. Experiments with reverse stream mufflers having nonperforating dividing fins show that there is a very material increase inback pressure, as compared to that of straight stream muiilers of thesame capacity, due to the fact that the entire gas stream is completelyreversed two times in the former structure, Whereas according to myinvention there is a progressive transfer of exhaust gases from thecompartment l as large.

I enclosing tube 6 to the compartment I 6 of tube 1, and thence on intocompartment I 'I of tube 8. 'Ihis transfer action more than comperisatesfor or neutralizes the increase in back pressure set up by the tworeversals of the main stream. 'Ihus the part of the gas stream goingthrough the reversing chambers I0 and II is approximately one half thatwhich would pass through a reverse stream muiiler of the nonperforatedfln type, and consequentlythe action is equivalent to that obtained witha conventional muffler having an expansion chamber two times Thisprogressive transfer or merging of impulses also results in a highlyefficient scavenging action, as the gases are not trapped inside theouter wall as is the case in muiilers of conventional acousticstructure, but are constantly passing along the inner circumference ofthe shell from one chamber to the next so that the entire muier becomeshot and is maintained at a temperature above the condensation point,even in cold weather and under conditions of intermittent and slowdriving.

'I'he modified form of the invention shown in Figures 4, 5 and 6functions in substantially the same manner as the preferred form justdescribed. In this modification the gas passage or tube 'I ofthepreferred form is eliminated and the reverse gas passage 20 is formed bytwo spaced parallel dividing fins or plates 2I and 2| of a Width equalto the diameter of shell I and which extends from one plate 9 to theother plate 9. The outer end of plate 2| is perforated as at 22 and theinner end of plate 2l is perforated as at 23. y The exhaust gases flowoutwardly or rearwardly through tube 6 thence into reverse chamber I0and back through passage 23 to and through reverse chamber II into andforwardly through tube 8. It will thus be seen that communicationbetween tubes 6 and 8 can be had only indirectly through passage 20.

Having thus described my invention, what I claim is:

A reverse stream muffler comprising an imperforate shell having endwalls, plates spaced from the end walls to form reversing chambers, a,perforated tube extending between said plates and communicating atopposite ends with said reversing chambers, a pair of gas communicatingtubes, one of said tubes communicating at one end with one of saidchambers and at its other end extending into and through the other ofsaid reversing chambers and its end wall, and the other of said tubescommunicating at one end with said last chamber and extending at itsother end into and through said first chamber and its end wall, theportions o-f'the tubes extending through the said reversing chambersbeing solid and the portions extending between the said plates beingperforated, a plurality of fins radiating from the axis of said shellextending between said plates and forming walls between said tubes, saidns subdividing said shell into three compartments one for saidperforated tube and one each for said gas tubes, the fin separating saidgas tubes being solid and the fins between the perforated tube and thegas tubes being perforated, and a packing of foraminous materialsubstantially filling said compartments.

